1. Field of the Invention
The present invention relates to a universal serial bus (USB) network interface controller and an operation mode switching method thereof. More particularly, the USB network interface controller and the operation mode switching method thereof according to the present invention can switch between different modes of USB transmission with a host when different wireless network access points are connected.
2. Descriptions of the Related Art
The universal serial bus (USB) input/output (I/O) interfaces have the advantages of supporting Hot-Plug and Plug-n-Play and having a high transmission speed, so they have been widely used in various computer peripheral devices. One of the common applications of the USB I/O interfaces is the USB wireless network controller card. Specifically, the USB wireless network controller card connects with a computer host mainly via a USB I/O interface and transmits data between the computer host and an external wireless network access point via the USB I/O interface.
Most of wireless network transmission specifications (e.g., 802.11a/b/g/n) commonly used at present transmit data in units of Mbps (mega bits per second), so USB wireless network controller cards adopting the USB 2.0 specification (with a maximum data rate of 480 Mbps) for data transmission with a computer host can substantially satisfy the needs for the data transmission rate between wireless networks and computer hosts in most cases.
However, with advancement of the wireless network technologies, high-speed wireless network transmission specifications (e.g., 802.11ac) that transmit data in units of Gbps (giga bit per second) have come into being. In this case, when a wireless network controller card adopting the USB 2.0 specification for connection with a computer host connects to a high-speed wireless network, data received by the USB wireless network controller card from the high-speed wireless network cannot be transmitted to the computer host timely because the maximum data rate of USB. 2.0 is only 480 Mbps. This leads to a bottleneck in data transmission between the high-speed wireless network and the computer host. As a primary solution to this problem, the USB 3.0 specification allowing for a maximum data rate of 5 Gbps has been introduced in some wireless network controller cards for data transmission with the computer host.
However, for USB wireless network controller cards that adopt the USB 3.0 specification for data transmission with the computer host, because the USB 3.0 specification operates at an operation frequency of 2.5 GHz, so the radiation and signal coupling caused during physical transferring of data signals in the buses will cause serious interference to wireless networks (e.g., 802.11b/g/n) that use frequency bands around 2.4-2.5 GHz for data transmission. Consequently, it is impossible to effectively accomplish the data transmission between the wireless network and the computer host when a USB wireless network controller card adopting the USB 3.0 specification is used.
Accordingly, an urgent need exists in the art to provide a solution that allows a USB wireless network controller card to effectively accomplish data transmission between different wireless networks and computer hosts but still with reduced signal interferes so as to improve flexibility in use of the USB wireless network controller card.